This document describes the key parts and functions of a neuron. It discusses the soma, dendrites, axon and myelin sheath. The soma contains organelles and extends into dendrites and an axon. Dendrites receive signals and the axon transmits output signals coated in a myelin sheath for insulation and faster transmission. The document also briefly discusses myelination, transport within neurons, ion channels, and classification of neurons.

3.  Cell body (soma)
 Axon
 Dendrites

4. Axon of another
neuron
Cell BodyDendrites
Axon
Myelin
Sheath
Dendrites of
another neuron

6.  Soma or prikariyon
 Nucleus and cytoplamic organelles
 Nissels granules = RER
 Cytoskeletal proteins like neurofilaments
,microtubules , actin microfilaments
 Nucleus contain one or two nucleolus ,and no
centriole
 Terminally differentiated cells

7.  Soma extend into dendrites on one end and
axon on the other
 Membrane called plasmalemma

8.  Numerous short extensions from cell body
 Increasing surface area
 Dendritic spines
 Receive incoming signals and transmits them
 Helps in protein synthesis
 Helps in generating ACTION POTENTIAL

10.  Axon fibers form the nerve
 Long cylindrical process extends away from cell
body
 Transmits output signals (Action Potential )
 Contains organelles , cytoskeleton, axoplasm
 Axon hillock - initial segment portion of neuron
 Axon terminal – axon divides into several
processes and has synaptic knobs
 Buttons contains neurotransmitters

12.  It’s a protective insulator covering of the axon
 Formed by schwann cells
 Double layer membrane of a single schwann
cell wraps itself several times around axon
 1 mm in length , 8 -10 micrometer in
thickness
 Layers stick to each other due to protein p0
 Schwann cell nucleus lies in the outermost
layer

16.  Nodes of Ranvier
 Internodal distance is 1-2mm and each node is
0.5-1 micrometer

17.  Increases speed of conduction
 It reduces energy expenditure by the cell
 Provides protective covering of the axon

18.  Myleniated Axons
 Unmyelinated Axons

19.  Different neurons in body shows diff time of
myelination
 Starts early as 4th month of fetal life and
completes by 2 years

20.  Transfer of substances between cell body and
axon terminal
 For the development of neuron
 Bi-directional transport

21.  Anterograde transport
 Retrograde transport
 Transneuronal transport

22.  From ell body to axon terminal
 Mainly for neurotransmitters
 Two types – fast and slow
 Fast – 400mm/day by kinesin
 Slow- 0.5 – 2 mm/day
 Slow transport helps in nerve repair

23.  From axon terminal to cell body
 200mm /day done by dynin
 Keeps soma informed about synaptic
environment
 Transports viruses such as varicella Zoster ,
rabies
 Transport toxins
 Transports nerve growth factor

24.  Voltage gated Na channels are mainly
concentrated on nodes of ranvier
 Voltage gated Ca channels are mainly present
at the axon terminal for neurotransmitter
secretion

25.  Based on function
 Myelination
 Erlanger and gasser classification

27.  Demyelinating diseases
1) multiple sclerosis
2) Gullian barre syndrome

28.  Wallerian degeneration

29.  5 grades
 1st-transient loss of function
 2nd- severe injury due to prolonged pressure,
intact endoneurium complete recovery but
delayed
 3rd- severe damage to endoneurial sheath
 4th- disruption of nerve fasciculi
 5th- complete transection

31.  Neurotrophins
 Other growth factors ( FGF,IGF-1, PDGF ,
CNTF,GDNF)

32.  Nerve growth factor
 Brain derived neurotrophic factor
 Neurotrophin-3
 Neurotrophin 4/5